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Cardiovascular System > Electrical Activity of the Heart > Flashcards

Electrical Activity of the Heart Flashcards

1
Q

Calcium is released from the

A

Sarcoplasmic reticulum

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2
Q

All cells of the heart are connected

A

Physically and electrically

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3
Q

What allows for physical connection of cells

A

Desmosomes

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4
Q

What allows for electrical connection of cells

A

Gap junction

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5
Q

Desmosomes and gap junctions together form

A

Intercalated discs

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6
Q

Cardiac muscle froms a

A

Functional syncytium

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7
Q

Action potential of cardiac muscle

A

250ms

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8
Q

Why can cardiac muscle not exhibit tetanic contraction

A

Due to long refractory period

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9
Q

Tetanus

A

Sustained contraction

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10
Q

What regulates the contraction of cardiac muscle

A

Calcium ions entry from outside the cell

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11
Q

Cardiac muscle can only contract in the presence of

A

Calcium ions

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12
Q

More calcium ions results in

A

Greater strength of contraction

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13
Q

Cells with unstable resting membrane potentials act as

A

Pacemakers

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14
Q

2 types of cardiac muscle

A

Non-pacemakers and pacemakers

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15
Q

Resting membrane potential of non-pacemaker cardiac muscle is maintained by

A

Potassium ions leaving the cell

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16
Q

Initial depolarisation in non-pacemaker cardiac muscle occurs by

A

Entry of sodium ions into cell

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17
Q

Plateau in non-pacemaker cardiac muscle is reached by

A

Entry of calcium ions via L-type voltage gated channels and potassium ions leaving the cell

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18
Q

Repolarisation in non-pacemaker cardiac muscle occurs by

A

Calcium ions leave the cell and potassium ions enter the cell

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19
Q

Action potential on pacemaker cardiac muscle occurs by

A

Entry of calcium ions inside the cell via L-type channels

20
Q

Pacemaker potential/pre-potential occurs by

A

Gradual decrease (leave) of potassium ions inside cell, early increase (entry) of sodium ions and late increase (entry) of calcium ions via T-type channels

21
Q

Autorhythmic

A

Heart has its own rhythm

22
Q

How is the heart autorhythmic

A

By pacemakers always reaching threshold and contraction

23
Q

Modulators of electrical activity

A 
Sympathetic and parasympathetic systems
Drugs
Temperature
Potassium ions
Calcium ions
24
Q

Effect of calcium ion channel blockers

A

Decrease force of contraction

25
Q

Effect of cardiac glycosides

A

Increase force of contraction

26
Q

Effect of increase of temperature

A

Increases electrical activity

27
Q

Effect of hyperkalemia

A

Fibrillation and heart block

28
Q

Heart block

A

Smaller electrical currents causing everything to work much slower than it should

29
Q

Effect of hypokalemia

A

Fibrillation and heart block

30
Q

Effect of hypercalcemia

A

Increased heart rate and force of contraction

31
Q

Effect of hypocalcemia

A

Decreased heart rate and force of contraction

32
Q

Sinoatrial node

A

Node containing the most pacemakers

33
Q

Function of sinoatrial node

A

Causes atrial excitation and sets the pace for the rest of the heart (0.5m/s)

34
Q

Location of sinoatrial node

A

Right atrium

35
Q

Annulus fibrous

A

Fibrous tissue that separates atrium and ventricle

36
Q

Atrioventricular node is also known as

A

Delay box

37
Q

Function of atrioventricular node

A

Slows down excitation until the atrium is finished contracting (0.05m/s)

38
Q

Bundle of His function

A

Conducts the electrical impulses from the atrioventricular node to the purkinje fibres

39
Q

Function of purkinje fibres

A

Cause ventricle excitation (5m/s)

40
Q

Bundle of His divides into

A

Purkinje fibres

41
Q

How are large extracellular electrical waves formed

A

Summation of many small extracellular electrical potentials

42
Q

Electrical activity can be recorded at the periphery as an

A

ECG (electrocardiodiagram)

43
Q

P wave of ECG corresponds to

A

Atrial depolarisation

44
Q

QRS complex corresponds to

A

Ventricular depolarisation

45
Q

T wave corresponds to

A

Ventricular repolarisation

46
Q

2 things that ECG can indicate

A

Disorders of conduction

Disorders of rhythm

Cardiovascular System (27 decks)

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